Apparatus for making articles from powdered metal briquets



Aug. 20, 1957 J. B. BRENNAN APPARATUS F OR MAKING ARTICLES FROM POWDEREDMETAL BRIQUETS Filed Aug. -8, 1952 QT'TOBJVES.

United States Patent C APPARATUS FOR MAKING ARTICLES FROM POWDERED METALBRIQUETS Joseph B. Brennan, Cleveland, Ohio Application August 8, 1952,Serial No. 363,317

1 Claim. (Cl. 22-75) The present invention relates generally asindicated to an apparatus for making articles from powdered metalbriquets and more particularly to certain improvements in apparatus forcarrying out the methods and processes disclosed in my co-pendingapplications Serial Nos. 104,369, 161,344, 202,707, all now abandonedand 252,938. This invention also relates to turbine blades.

It is one object of this invention to provide an apparatus by whichaccurate articles of desired denseness (porous or non-porous) may beformed from powdered metal briquets.

It is another object of this invention to provide an apparatus by whichand with which a powdered metal briquet may be partially or completelyfused while contained within a non-distorting heat-resistant enclosure,which enclosure may, in some instances, be wholly or partly of amaterial which imparts desired physical or chemical properties to thebriquet therein or which bonds to the briquet.

Other objects and advantages of my invention will appear as thedescription proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claim, the following description and the annexed drawin-gs setting forth in detail certain illustrative embodiments of theinvention, these being indicative, however, of but a few of the variousways in which the principles of the invention may be employed.

In said annexed drawings:

Fig. 1 is a cross-section view of a powdered metal briquet andsurrounding enclosure;

Fig. 2 is a cross-section view similar to Fig. 1 except that a falsepiston is included in the enclosure in contact with the powdered metalbriquet;

Fig. 3 is a cross-section view showing the false piston of Fig. 2replaced by a piston which is adapted to exert pressure on the powderedmetal briquet when the latter is melted;

Fig. 4 is a cross-section view of a special form of powdered metalbriquet with a surrounding solid metal band to which the powdered metalis to be bonded or alloyed; and

Fig. 5 is a cross-section view of one form of apparatus which may beemployed for the practice of the present method.

Referring now more particularly to the drawing and first to Fig. 1thereof, the powdered metal briquet 1 is formed in well-known manner bythe mechanical consolidation of the metal powder in suitable diesprovided with cavities of the desired shape and size. The pressurerequired to form the briquet 1 will, of course, vary according to theparticular metal which is used; and, except in the case of low-meltingpoint metals, the pressed compact or briquet is mechanically weak andmust be handled with care. Any of a variety of different metals andalloys may be employed for forming the metals and alloys from whichpowdered metal briquets may be formed are: RC 130 B or Ti Alloy 150A,whose powdered metal briquet 1. Examples of some of the compositions areas follows: N. N. 4%, Al 4%, O 2%, N .1% max, and Ti balance; and Fe1.3%, Cr. 2.7%, O .25 N .02% max., C .02% max, and Ti balance.

After the briquet 1 has been formed, it is enclosed in a body 2 ofheat-resistant material, usually a ceramic material including carbon,mica, plaster of Paris, asbes- 0 tos, stabilized zirconium oxide, andother heat-resistant and preferably, but not necessarily, non-metallicmaterials which can be heated to at least the melting point of thebriquet without melting, burning, or otherwise ren-= dered inoperativeby the melting of the briquet therein. Enclosing of the briquet 1 withinthe body of a heat.-

resistant material 2 may be done as is disclosedin my aforesaidco-pending applications Serial Nos, 161,344 and 202,707.

In the case that the enclosure 2 is in the form of ,a mold made of twoor more pieces, the same may be pre-fired or fused so that said moldwill have a very close fit in the guide portion of the apparatus whichwill be presently described.

In Figs. 2 and 3 the briquet 1 is enclosed within a composite enclosurewhich comprises a body 3 Of heatresistant material and a plug 4 of anydesired material such as metal, said plug being positioned adjacent oneend of the briquet 1 so as to form therewith and with the body 3 acylinder for a piston .5. It can be 69 from Fig. 3 that when the briquet1 is fused, pressure on the top of the piston 5 will cause the end ofthe piston to exert pressure on the top of the fused briquet. The degreeof compacting of the melted briquet 1 is determined by the distance 6which is additionally selected so that the article Will be of thedesired dimensions in the direction of pressure application thereon.Thus, where the briquet is of a tubular form as shown in Figs, 1 to 3,the axial dimension thereof will be somewhat gt aifil' than that of thefinished article because of the reduction in bulk owing to the fusingthereof and mechanical consolidation in addition, when the piston 5 isemployed as shown in Fig. 3. The diameters of the briquet can, ofcourse, be made to correspond with the desired final diameters of thearticle except to take into account shrinkage owing to a thermalcontraction.

In Fig. 4, the powdered metal briquet 7 is formed inside a continuoussolid metal band Sand the composite briquet 7 and band 8 will beenclosed in heat-resistant material as shown in Figs. 1 or 2 and uponfusing of the briquet 7, the same will become bonded to or alloyed withthe band 8 according to the particular selection of materials for thebriquet and for the band .8.

In Fig. 5, there is shown a preferred form of appa= ratus through whichthe briquets and surrounding enclosures of Figs. 1 and 3, for example,are adaptfedto pass. In Fig. 5, the composite enclosures and briquetstherewithin are represented .by the reference numeral '10 and forpurposes .of illustration, these composite enclosures and briquets areof the form illustrated in Fig. 3.

At the top of the apparatus, there is provided ,a guide tube 11 in whichthe units 10 aresuperirnposed one upon the other with the pistons 5. atthe top of .each unit. These units 10 are fed downwardly as by means ofpowerdriven chains or belts 12 which run over sprocket wheels or pulleys14 and 15. The opposed parallel portions of the belts 12 may be pressedinto frictional engagement with the units 10 .therebetween as by meansof spring loaded blocks 16. It is to be understood ,that pos tiye feedmeans maybe employed if desired and in such case, the exterior of theunits 10 may be provided with gear teeth or like formations for meshingwith tee h on the wheels 14 or with spaces in the opposed chains 12. One

pair of the wheels 14 or 15 will be power-driven and as evident,downward feeding of the units 10 may be accomplished at a constantspeed.

Or the units 10 and pistons may be successively pushed down through tube11 by a reciprocating hydraulic ram.

The apparatus below the just-described feedingdevice comprises a guidetube 17 which may be formed of graphite or like material having anon-oxidizable coating on its inner surface. Such coating may be ofstabilized zirconium oxide or similar refractory material.

The guide tube 17 thus interiorly coated serves to seal the units fromthe surrounding atmosphere and also to provide a precision guide. Saidguide tube 17 also alleviates gas contamination.

The upper portion of the guide tube 17 has a heating chamber 18therearound for pre-heating the units 10 as they pass downwardly throughthe guide tube 17. Said heating chamber may be heated by any suitablemeans such as the electric heating element 19, or by hot inert gasescirculated through said chamber 18, or by molten material contained inthe chamber 18 and heated to predetermined temperature by any suitablemeans.

As the units pass downwardly through the heating chamber 18,substantially all of the gases are expelled therefrom.

Below said pre-heating chamber 18 or as shown in the lower portion ofsaid chamber, there is a high frequency heating coil 20 which encirclesthe guide tube 17. Thus, as the units 10 move downwardly at constantspeed, the pre-heated briquets 1 will be further heated and melted orfused from the bottom thereof upwardly; and, because the gases have beenexpelled by the pre-heating of said briquet 1 and the enclosure 3therearound, the melted metal will completely fill the space in theenclosure without any trapped gas pockets. Where the pistons 5 areemployed in association with the enclosures 3, the resistance todownward movement of the units 10 as will be hereinafter explained willcause the end of the piston 5 to exert pressure on the fused briquet 1for densifying the same and further causing the melted briquet tocompletely fill the cavity within the enclosure 3 including sharpcorners, etc.

The chamber 18 is preferably operated under a vacuum or partial vacuumwith an inert gas such as argon therein when desired by means of avacuum pump and exhaust pipe system attached thereto.

In passing downwardly through the high frequency heating coil 20, thebriquets 1 within the units 10 are successively completely melted andafter the melting has been completed, the units 10 now pass through acooling unit 21 which surrounds the guide tube 17 and through which asuitable cooling medium is adapted to be circulated. Therefore, as theunits 10 pass downwardly through the portion of the guide tube 17located within the cooling unit 21, the enclosures 3 and melted briquets1 therewithin are cooled to effect solidification of the briquet 1.

Thus, when the units 10 are discharged from the lower end of the guidetube 17, the finished accurate articles of desired density are removedfrom within the enclosures 3 by breaking away the enclosures 3 where thelatter is of one-piece construction or by opening the enclosure forremoval of the article therewithin in the case that said enclosure isformed of two or more mating pieces.

Where the enclosure 3 is formed of graphite or of a ceramic materialhaving carbon therein a certain amount of carbon pick-up may be obtainedin this type of fusion casting whereby at least the outer skin of themelted and subsequently solidified briquet 1 is made more abrasiveresistant. For example, in casting titanium alloys, the outside skin ispartially converted to titanium carbide.

In order that a desired resistance may be built up against the downwardmovement of the units 10 through the guide tube 17, there is disposedadjacent the lower end of said guide tube a friction mechanism whichincludes for example, a fixed shoe 22 engaging one side of superimposedunits 10 and a movable spring load shoe 23 which resiliently pressesagainst the opposite side of said units 10. The pressure which the shoe23 exerts against the units 10 may be varied by adjusting thecompression of the spring 24 by means of a suitable adjusting screw 25.Instead of the particular resistance unit shown at the bottom of Fig. 5,other well-known expedients may be employed. For example, a mechanismsuch as used for downward feeding may be positioned adjacent the lowerend of the guide tube 17 and instead of positively driving one pair ofthe Wheels 14 or 15, adjustable brakes may be associated therewith forbuilding up the desired resistance against downward movement of theunits 10, or a reciprocating hydraulic ram may be used to assist and/orcontrol the resistance for compression desired.

When the briquet is of the form illustrated in Fig. 4, it is possible tobond the solid metal 8 to the powdered briquet 7 by using the apparatusillustrated in Fig. 5. It should be further noted that the briquets 1may be made of spherical particles of metal or loose spherical particlesmay be loaded into a mold cavity and by fusing the spherical particlesonly partly, the final article will be partially permeable and will beuniformly orificed since in that case, only the contacting portions ofthe spherical particles will bond together.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in the following claim, or the equivalent of such, beemployed.

I therefore particularly point out and distinctly claim as my invention:

Apparatus for making articles from powdered metal briquets comprisingopen top molds containing such briquets, pistons fitted into therespective molds to bear on the top of the briquets therein, adownwardly extending guide member, means for feeding said molds andpistons downwardly through said guide member in superimposed relationwith each piston engaged by the bottom of the mold thereabove,pre-heating means around said guide for heating said molds and briquetstherein and thus expelling gases therefrom as said molds are moveddownwardly through said guide member, heating means effective toprogressively fuse the briquets in said preheated molds from the bottomupwardly as said molds continue to move downwardly through said guidemember, artificial cooling means for solidifying the fused metal in saidmolds, and means below said heating means opposing downward movement ofsaid molds whereby said pistons are actuated into the respective moldsby the molds thereabove so as to bear on the fused metal.

References Cited in the file of this patent UNITED STATES PATENTS741,776 Dodge Oct. 20, 1903 2,149,510 Darrieus Mar. 7, 1939 2,422,439Schwarzkopf June 17, 1947 2,480,076 DeMarinis Aug. 23, 1949 2,557,971Jacklin June 26, 1951 2,581,252 Goetzel Jan. 1, 1952 2,716,790 BrennanSept. 6, 1955 FOREIGN PATENTS 611,466 Great Britain Oct. 29, 1948619,634 Great Britain Acc. Mar. 11, 1949 115,143 Sweden Aug. 9, 1945120,178 Sweden Sept. 11, 1947

